| TS-1 titanosilicate, as an important selective oxidation catalyst, is of great value and has a great advantage in the industrial application. Since the 1980s, in order to acquire the low-cost TS-1 catalyst with a high performance, a large number of researchers have made very excellent achievements in reducing its cost, and improving the coordination state of titanium, which have extended the industrial application value of TS-1. In this essay, we have tried and developed a new cheap synthetic route through the control of the synthesis procedure and the chemical composition of synthetic gels. We partly replaced tetrapropylammonium hydroxide (TPAOH) with cheaper tetrapropylammonium bromide (TPABr) as an organic template, and reduced the total usage amount of TPA+, then successfully acquired a kind of microsized brick TS-1 crystals with a relatively good crystallinity. This kind of microsized brick TS-1 crystals are of monocrystal structure, which has a relatively thin thickness in b axis direction along the 10-ring straight channel, resulting in a low resistance to mass transfer for the reaction occurring in the straight channel. Such a morphology would be beneficial to improve the catalytic performance of this kind of microsized brick TS-1 crystals. In addition, we conducted a post-treatment on this brick TS-1 with an appropriate amount of NaOH partly replacing TPAOH. This low-cost post-treatment made the surface Ti content higher and generated a lot of mesopores, meanwhile avoiding the poisoning of the Ti site, this resulted in an excellent catalytic performance. At the same time, we also tried to add a small amount of sucrose in the synthetic gel of TS-1 and successfully obtained relatively smaller brick TS-1 with a good crystallinity. Its catalytic performance is nearly equivalent to traditional nano-sized TS-1. Al-containing TS-1 (A1-TS-1) has also been synthesized. These work may enrich the cheap methods for synthesizing TS-1 and promote the development of low-cost TS-1 catalysts. |
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